<template>
  <div id="app">
    <div class="subject" v-for="(item,index) in arr" :key='index'>
      <span>{{item.num1}}</span>
      <span>+</span>
      <span>{{item.num2}}</span>
      <span>=</span>
      <input type="number" v-model='item.result' />
      <button @click.prevent='sum(index)' :disabled="item.submitted">提交</button>
    </div>
  </div>
</template>

<script>
export default {
  data () {
    return {
    }
  },
  props: ['arr'],
  methods: {
    sum (index) {
      this.$emit('sum', index)
    }
  }
};
</script>

<style scoped>
.subject {
  margin: 5px;
  padding: 5px;
  font-size: 20px;
}
.subject span {
  display: inline-block;
  text-align: center;
  width: 20px;
}
.subject input {
  width: 50px;
  height: 20px;
}
</style>